<!DOCTYPE html>
<html>

	<head>
		<meta charset="utf-8" />
		<title>后台系统登录页面</title>
		
		<style type="text/css">
.code{
background-image:url(111.jpg);
font-family:Arial,宋体;
font-style:italic;
color:green;
border:0;
padding:2px 3px;
letter-spacing:3px;
font-weight:bolder;
}
.unchanged {
border:0;
}
</style>
<script language="javascript" type="text/javascript">
var code ; //在全局 定义验证码
function createCode(){ 
code = new Array();
var codeLength = 4;//验证码的长度
var checkCode = document.getElementById("checkCode");
checkCode.value = "";

var selectChar = new Array(2,3,4,5,6,7,8,9,'A','B','C','D','E','F','G','H','J','K','L','M','N','P','Q','R','S','T','U','V','W','X','Y','Z');

for(var i=0;i<codeLength;i++) {
   var charIndex = Math.floor(Math.random()*32);
   code +=selectChar[charIndex];
}
if(code.length != codeLength){
   createCode();
}
checkCode.value = code;
}

function validate () {
var inputCode = document.getElementById("input1").value.toUpperCase();
var name2 = document.getElementById("name1").value.toUpperCase();
var psd2 = document.getElementById("psd1").value.toUpperCase();

if(inputCode.length <=0) {
   alert("请输入验证码！");
   return false;
}
else if(inputCode != code ){
   alert("验证码输入错误！");
   createCode();
   return false;
}
else {
	return true;
   if(name2!="admin")
   {
   	if(psd2!="admin")
   	{
   		window.open("index.html")
   	}else{
   		alert("密码不正确");
   	}
   	alert("用户名不正确");
   }
   
    
}
}
</script>
	</head>

	<body onLoad="createCode();">
		<center>
			<B>登录页面</B>
			<table>
				<tr>
					<td>用户名</td>
					<td>
						<input type="text"id="name1"/>
					</td>
				</tr>

				<tr>
					<td>密码</td>
					<td>
						<input type="password"id="psd1"/>
					</td>
				</tr>
				<tr>
					<td>
						验证码
						<br>
					<input type="button" id="checkCode" class="code" style="width:60px" onClick="createCode()" /> 
					</td>
					<td>
						<input type="text" id="input1"width="10px"/>
					</td>
					
				</tr>
			</table>
			 
 
<input id="Button1" onClick="validate();" type="button" value="确定" />
		</center>
	</body>

</html>